Circuit controller



Aug. 10, 1943. Q STANSBURY CIRCUIT CONTROLLER Filed July 29, 1940 Patented Aug. 10, 1943 UNITED STATES PATENT OFFICE CIRCUIT CONTROLLER Carroll Stansbury, Wauwatosa,

Cutler-Hammer, Inc.,

notation of Delaware Application July 29, 1940, Serial No. 348,169

4 Claims.

This invention relates to improvements in circuit controllers, and although not limited thereto is especially adapted to the control of electric motors which are startedby varying the voltage impressed upon their windings in steps which succeed one another at given time intervals.

A primary object of the invention is to provide an improved circuit controller of the aforementioned type in which [the time intervals between the different steps are individually adjustable.

Another object is to provide an improved con troller of the aforementioned type which involves the use of electrically stored energy.

Another object is to provide a unitary conltrol relay comprising a single electromagnetic winding and a plurality of armatures operable to afford individual circuit commutations which are independently adjustable.

Another object is to provide a relay of the aforementioned type which is positive inoperation and which is capable of commutating currents of considerable magnitude.

In Patent No. 2,205,676, granted June 25, 1940, to Stansbury et al., and assigned to the same assignee as the present invention, a circuit controller is disclosed of which the present invention is an improved and simplified type and which is capable by virtue of its construction to directly commutate the heavy main circuit currents of an electric motor. The accompanying drawing is illustrative of an embodiment of the invention.

In the drawing,

Figure 1 is a circuit diagram embodying the invention.

Figs. 2, 3 and 4 illustrate the relay employed in the system shown in Figure 1, and

Fig. 5 is a fragmentary detail view of certain parts of the relay shown in Figs. 2 to 4, inclusive.

Referring first to Fig. 1 of the drawing, the same illustrates a direct current shunt motor, having an armature l and a shunt field winding 2. Energy for the motor and the control circuits is supplied by the bus bars U, 1?. One terminal 01' the armature .l and one terminal of the shunt field 2 are connected together and are connectable to the line L through normally open main COllltEtClis 3 of an electromagnetic main switch 3, having also an energizing winding 3", normally open auxiliary contacts 3 and normally closed auxiliary contacts 3". The other terminal of the armature l is connected to line L? through a starting resistor 4, while the other terminal of Wis, assignor to Milwaukee, Wis., a corthe field winding 2 is connected to line L through an adjustable shunt field resistor 5.

The resistor 5 may be short-circuited by closure of a normally open contact 6 of a relay 6, which has an energizing winding 6 and in addition has normally closed contacts 6* and normally open contacts 6. The construction of relay 6 will be more fully described hereinafter in con nection with Figs. 2 to 5, inclusive.

'I'hesystem also includes a normally open push button switch 1, connected between one terminal of winding 3 and line L and in parallel with normally open contacts 3. The other terminal of winding 3 is connected in series with a normally closed push button switch 8 and a resistor 9 to line L. Normally open contact (i is connected in parallel with resistor 9. One terminal of winding 6 is connected through norm-ally closed contact 3 to line L while the other terminal of said winding is connected to line L A condenser II) which may be variable is connected in series with a resistor II, which also may be variable, to form a circuit in parallel with winding 6.

r The relay 6 shown in detail in Figs. 2 to 5, inclusive, comprises a core I! which is surrounded by the energizing coil 6. The magnetic circuit which includes the core [2 isv continued by a U-shaped frame l3, formed of a rectangular strip of magnetic material which embraces the coil 6, the limbs of frame I3 extending to a plane substantially flush with the outer end ii of core [2 and at a right angle to its major axis; said outer end t2 being of elongated substantially rectangular contour, as best illustrated in Fig. 2. The forward edge of the lower limb of the frame I3 cooperates with a metal bracket l3 attached to the latter to provide bearings for pivotal support of the reduced lower'ends of the armatures I4, l5 and I6 which carry at their other ends the movable members of contacts 6*, 6 and 6, respectively. The stationary cooperating elements of contacts 6 and 6 are supported by but insulated from the upper limb of the frame l3, as by means of an insulating block 21 attached to the latter.

The armatures are provided with biasing springs I4, I5 and i6, respectively, which may conveniently be attached at one end thereof to a rear lug or flange formed upon bracket 13*. Said springs may be provided individually with tension adjusting means (not shown). The armatures l5 and I6 are provided with normally open contacts, and the armature I4 is .provided with reversely arranged normally closed contacts.

The armature M has attached thereto, as by riveting, welding or otherwise, a magnetic extension or keeper ll which in the closed position An adjustable abutment screw :5 is provided a for each armature by means of which the air gap between it and the portion l2 of core |2 may be adjusted, to thereby adjust the magnetic flux value at which it is released. The holding magnet I9 is supported from an insulating panel 22 which is rigidly connected to the frame [3 by 'two brackets 23 and 24, the latter being connected to the free terminal of the coil 2| and in turn provided with a terminal which is connected to the common point between armature and resistor 4 (see Fig. 1).

The lever H is prevented from directly contacting the pole shoes I8 by a non-magnetic spacer 26- which in the present device (see Fig. 4) isin the form of a layer or coating of vitreous enamel upon that portion of the inner surface of lever I! which would otherwise engage pole shoes l8. Thus when the contacts 6 are closed and current passes therethrough, the armature H is attracted by the action of the coil 2| so as to hold the contacts firmly closed after the armature H has been released by the relay 6 as will be explained more in detail hereinafter.-

The system described functions as follows: When the lines L and L are energized, the relay 6 is energized by a current flowing from L over contacts 3*, through coilii to 1?. The condenser III, being connected in parallel with coil 6 is charged to the potential of the latter. Also, as a result of the energization of relay 6, the contacts 6 are opened and contacts 6 and 6 are closed.

If it is now desired to start the motor I, the pushbutton switch I is momentarily depressed, thus closing a circuit from L over switch 1 through coil 3*, switch 8, contacts 6 to L. The

' switch 3 completes its own maintaining circuit through closure of normally open contacts 3 thereof so that the switch I may be released and the switch 3 stays closed. Energization of switch 3 also closes contacts 3 which connects the motor armature l across the lines in series with resistor l and simultaneously energizes the field winding 2 through contacts 6 so that the motor starts with full field strength. At the same time the contacts 3' open, thereby disconnecting the coil 6 from the lines. The magnetic field of the relay 6 tends to' decay while the condenser l tends to discharge through the coil 6"- and resistor II, the discharge current being in such direction as to retard the decay of the flux. The rate of permitted decay of said flux depends upon the relative values of the inductance of coil 6 the capacitance of condenser l0 and the resistance value of resistor The various armatures of relay 6 are so adjusted that during decay of the flux the armature I is first released, thereby inserting the protecting resistor 9 in series with the coil 3. Shortly thereafter armature I4 is released, closing its contacts 6 and short circuiting the starting resistor 4, the armature current now flowing through coil 2| and over contacts 6. Energizetion of coil 2| causes the magnet l9 (Figs. 2 to 4) to draw the armature extension l1 toward the pole shoes I8, thus increasing the pressure of he assaaoa contacts 6 against each other and holding them in firm engagement to prevent overheating and If it is desired to .stop the motor, the push button switch [is operated to open its contacts,-

thus deenergizing switch 3 and returning the elements of the system to their respective initial positions, as illustrated in Fi 1.

. It will be'apparent that the condenser It as well as the resistor may be made adjustable to vary the time constant of decay of the flux in relay 6 to thereby also vary the rate of commutation of the motor circuits. Furthermore if adjustment of the springs I49, l5 and [6 is provided this will enable adjustment of the rate of acceleration of the motor by variation of the value of the decaying pull on the respective armatures at which they will commutate their contacts. If desired, the relay 6 may be provided with a plurality of armatures and cooperating contacts for commutating several steps of main circuit accelerating resistors and it may also be provided with a plurality of field regulating contacts and cooperating armatures.

As best illustrated in ,Fig. 5, the stationary element of the contacts 6 is supported by but insulated from the rear end portion of the lefthand pole shoe l8 (Fig. 4)said pole shoe being in turn secured to bracket 23 for support by the latter.

Any suitable means may be provided for limiting-movement of the armatures l5 and I6 outwardly from the portion |2 of the core l2 or transversely with respect to each other. For example, I have shown a punched sheet metal guide-plate 28, which is preferably notched or cut away attwo points to freely accommodate the respective armatures l5 and |6-the outer ends of the notches being of reduced width to provide pairs of shoulders whereby outward movement of said armatures under the bias of springs l5 and I6 is limited. Armatures M, of course, has its outward movement limited as an incident to engagement of contacts ti associated therewith.

What I claim as new and Letters Patent is:

1. Circuit controlling means comprising, an electromagnetic switch having a plurality of magnetizable armatures, a magnetizable frame forming-with each of said armatures a magnetic circuit having a variable air gap between the respective armature and said frame to permit relative movement therebetween, circuit commutating contacts operable by said armatures,

desire to secure by magnetizing means for inducing a magnetic flux in said magnetic circuits, means for biasing the respective armatures individually to given positions thereof in opposition to the magnetic pulls thereon respectively and for permitting movement thereof to other positions when said fiux exceeds a given value, and electromagnetic means associated with at least one of said circuit commutating contacts and energized upon closure thereof, to amplify the biasing means upon its respective armature.

2. Circuit controlling means comprising, an electromagnetic switch having a magnetic circuit including a core and a plurality of movable armatures, a magnetizing winding adapted to induce a magnetic fluxin said magnetic circuit, individual means for biasing said armatures to a given posi-' tion in opposition to the magnetic pull thereon and to permit movement of said armatures to another position when the current in said winding exceeds a given value, and electromagnetic means associated with certain of said armatures and adapted to be energized in response to the position thereof to thereby amplify the effect of the biasing means thereon.

3. Circuit controlling means, comprising an electromagnetic switch having a plurality of magnetizable armatures, a magnetizable frame forming with each of said armatures a magnetic circuit having a variable air gap between the re-.

spective armature and said frame to permit relative movement therebetween, circuit commutating contacts operable by said armatures, magnetizing means for inducing a magnetic flux in said magnetic circuits, means for biasing the respective armatures individually to given positions thereof in opposition to the magnetic pulls thereon respectively and for permitting movement thereof to other positions when said flux exceeds a given value, and to return said armatures to said given positions individually upon decrease of said flux from said given value to another given value, and electromagnetic means associated with at least one of said circuit commutating contacts and energized upon closure thereof to amplify the efiect of said biasing means upon its respective armature.

4'. Current controlling means comprising a switch tending to close, a magnetic circuit including a core and a movable armature, an energizing winding to induce a magnetic flux in said core and armature for switch opening, said switch upon deenergization of said winding returning to closed position, a condenser associated with said winding to delay its deenergization and thereby delay reclosure of said switch, and electromagnetic means acting upon said switch in reclosing to insure a given contact pressure thereof but only after release of said armature under the influence of said condenser, thus permitting action of said condenser free from influence by said second mentioned electromagnetic means.

CARROLL STANSBURY.

CERTIFICATE OF CORRECTION. Patent No. 2,526,262. August 10, 1914.3.

CARROLL STANSBURY.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line '(0, claim 1, after "the" insert -effect of said-; and that the said Letters Patent should be read with this correction therein that the same' may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of November, A. D. 19145.

. Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

CERTIFICA'I'E 0F CORRECTION. Patent No. 2,526,262. August 10, 1914.5;

" CARROLL STANSBURY.

It is hereby certified that error appears in the printed specification of the above 'numbered patent requiring correction as follows: 'Page 2, second column, line 70, claim 1, after 'the" insert --effect of said-; and that the said Letters Patent should be read with this correction therein that the same may conform to the recorder the case in the Patent Office.

Signed and sealed this 9th day of November, A. D. 191;}.

v Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

